GUIDED WAVE PROPAGATION TIlKuUCill GYllOMAGNETIC MEDIA. II 941 



An example of a simple non-reciprocal system is indicated in Fig. 1(a). 

 Here a slab of ferrite is inserted into a rectangular waveguide parallel 

 to the narrow walls and closer to one of them. Several workers have 

 demonstrated that this arrangement and a similar arrangement in a 

 circular waveguide are non-reciprocal for what is essentially the dom- 

 inant mode. ' ' When the slab is centered in the guide we have a plane 

 of symmetry and the non-reciprocity vanishes. 



Another configuration of the transverse field type is represented by 

 the system shown in Fig. 1(b). Here a hollow ferrite cylinder is mag- 

 netized circumferentially and propagates a TEon-mode. It is clear that 

 any arrangement of this sort, which might, in principle, include conduct- 

 ing sheaths, internally or externally, or might have the ferrite extending 

 to an indefinitely large or small radius, cannot have any symmetry 



MAGNETIZING 

 FIELD Ho 



WAVEGUIDE ~ 



WINDINGS FOR 

 MAGNETIZING--, 

 CURRENT 



PROPAGATION 

 DIRECTION 



CIRCUMFERENTIAL,-' 

 MAGNETIC FIELD 



(b) 



Fig. 1 — (a) Rectangular waveguide and ferrite slab, (b) Circumferentially 

 magnetized ferrite cylinder. 



* It is expected that an article on this subject by S. E. Miller, A. G. Fox and 

 M. T. Weiss will appear in a forthcoming issue of the Journal. 



